Inside a pink house on a leafy suburban street in Curitiba, Brazil, sits a 75-year-old man wearing bright blue trousers, shades and skateboarding sneakers. He strokes a silvery, ZZ-Top style beard. Around him hundreds of cuddly toys pile up on shelves and mantlepieces: birds, bears and babies in a blaze of reds, greens and yellows. "Everything you see here is an instrument," the man beams, motioning excitedly towards his furry menagerie. "There are instruments everywhere!"

Welcome to the home of Hermeto Pascoal, one of Brazil's most eccentric, prolific and treasured composers and musicians, and a man once described by Miles Davis as "one of the most important musicians on the planet".

Now in his eighth decade, Pascoal – who makes a rare appearance at the Barbican in London on 20 November alongside an "all-star" British big band – claims he has no plans to retire. "Lots of artists of my age are stopping – I feel like I am just starting," he says, in his distinctive north-eastern accent. "In my head, there is always more stuff. Wouldn't it just be really tedious if a bunch of old guys from my generation all died or fell asleep on the stage? Our primary concern is innovation."

The word innovation has long been synonymous with Pascoal, whose talent for making music out of virtually anything has earned him such nicknames as the Magus.

A virtuoso pianist, accordionist and flautist, Pascoal has long preferred rather more unconventional ways of producing sounds and songs: napkins, carpets, chairs, pints of beer, body parts, kitchen utensils, animals even. A pig, famously, features on a 1977 album.

"I don't like to use ready-made instruments or sounds. I like to transform things into sounds and instruments," he admits. "I get given lots of instruments by people who admire me, but I rarely use them because I like to pick up any old thing and just start playing it, turning it into an instrument." He pauses, and adds: "I write sheet music for these dolls!"

Calling Pascoal a multi-instrumentalist is an understatement. Asked how many instruments he plays, he stammers for a few seconds, uncharacteristically lost for words. "Look, there isn't, there isn't … The quantity of instruments is infinite because of me – wherever I am is an instrument. A chair is an instrument. A table is an instrument. There are so many instruments."

"To me musicians are like painters. If he only plays one instrument, he has to at the very least change the style in which he plays his songs. Not play just one instrument in the same way, like those people who play classical music and just play classical music, or those who play jazz and only jazz. That is very tedious."

Pinning down Pascoal's musical style is equally complex. He rejects the terms jazz, Brazilian popular music (MPB), bossa nova, chorinho or forro, all of which are elements in his shows and recordings.

"I don't just play one style. I play nearly all of them," he boasts, during a two-hour interview at his home where he lives with his partner, the 32-year-old singer Aline Morena. Instead, he calls it musica universal. "It comes from the universe, so that's why I call it musica universal," he says. "It's an energy that never stops. It hovers over us wherever we are.

"It's not a fad. I don't like labels. But the only thing I can accept as a label is musica universal. Brazil is the country with the greatest number of peoples from around the world. So the world is Brazil. Brazil has the whole world here. So why shouldn't we be home to the music of the world?"

Hermeto Pascoal has spent much of the last four decades touring internationally, but he comes from a humble, rural background in north-eastern Brazil. He was born in Olho d'Agua, a tiny rural settlement near the town of Lagoa da Canoa, in the state of Alagoas. "I was born on 22 June 1936. It was raining; lots of rain."

While Pascoal's parents worked the fields, he and his elder brother taught themselves music. Pascoal, an albino, had extra incentive to stay inside and practise the flute and the accordion, away from the fierce sunshine. By the ages of eight and nine, they were commanding local dance parties.

In 1950, when Pascoal was 14, the family moved to Recife, capital of the state of Pernambuco, and he continued to develop his playing skills, performing on local radio shows. He later headed south to Rio de Janeiro and then São Paulo, where he formed the short-lived but highly influential Sambrasa Trio with the drummer and percussionist Airto Moreira during the 1960s.

It was Moreira who took Pascoal on his first international foray – a trip to the US that ultimately led to a meeting with Miles Davis, who went on to record two of his tracks on his 1971 album Live-Evil. It was the start of an international career that has seen Pascoal make a name for himself as one of the most productive composers around.

For one year in 1996, he set himself the task of composing a track a day – all recorded in a book called Sound Calendar. I tell Pascoal I'm impressed. "Young man, I composed five times more than this after the book came out," he replies. "I compose all the time, all the time. Yesterday I composed two!"

"When I'm in hotels, on the road, I don't even take my notebooks sometimes, to give myself a break from writing. But I can't. I get crazy to compose – just like people who use drugs or don't have their cigarettes."

"This one I wrote on the aeroplane," he goes on, clutching a Lufthansa food tray from a recent inflight meal. He has covered it in black semi-quavers and treble clefs. "It's the top of the food tray. But it's as marvellous, as important as any other track I've ever written.

"Songs are my friends. They are kids. My partners. My friends. You get it? They are characters. When a song comes into my mind, it's as if a person is visiting me. I start talking, I start chatting with them, I start writing, and nothing can stop me."

Pascoal's London show will see him reunited with a specially assembled big band with whom he first played in 1994 at London's Queen Elizabeth Hall. At the time John Fordham described the show as "one of the most electrifying jazz concerts on the South Bank in years".

"The repertoire is enormous. We always take a lot of songs," Pascoal says of the forthcoming show. "I don't make a selection – it could change in the middle of the show … We have to have loads of songs so when you feel something, you can play it."

There is at least one certainty about Sunday's gig: Pascoal will be joined on stage by two other heavyweights of Brazilian music, the harmonica player Gabriel Grossi and the mandolinist Hamilton de Holanda. Two of the most exciting young proponents of a new generation of Brazilian musicians, Pascoal calls them the "new gang".

Cuddly toys may also appear on the Barbican stage. "I'm going to take some dolls for the big band just to surprise the musicians. A time will arrive, and I'll hand them out to the musicians and they won't have a clue what is going on. They'll just say: 'Ah, that's Hermeto for you!'"

Back in Brazil, the spritely 75-year-old has plans for a new CD – recorded entirely with sounds produced by his own body – and plots to set up a music school called the Temple of Sound.